240 Brown : Algal periodicity 



floating in long ribbons. Material brought into the laboratory 

 produced numerous zoospores in a few hours. This form persisted 

 until the first of August, becoming rather rare at times. 



The only species found belonging to the order Cladophorales 

 was Cladophora glomerata. This species was present in the upper 

 part of stream no. I (see chart) throughout the year. During only 

 a few months in the spring, ranging from the middle of April to 

 the middle of June, was there much growth. During this time it 

 grew rapidly so as nearly to fill the channel of the stream. Its 

 growth was checked at the end of this time, doubtless by the water 

 becoming low, impure, and warm. During the rest of the year the 

 filaments that persisted were unhealthy looking, the cells had thick 

 walls and were crusty looking, due to particles of sand and diatoms 

 clinging to them. It was noticed in several places that where the 

 plant grew in swift water the filaments were much branched ; in 

 quiet flowing water there was but little branching. Cladophora was 

 not found in a healthy growing state in any of the ponds. Small 

 masses were found in some, but it was not in a healthy condition 

 and had doubtless floated in from a feeding branch. Cladophora 

 glomerata transferred from stream no. I to stream no. 2 and an- 

 chored in the latter failed to grow. This stream has purer water, 

 flows swiftly and has a relatively lower temperature than the first, 

 standing at about 12° C. continually. 



The only representatives of the order Siphonales found in the 

 regions studied were two species of Vancheria, V. sessilis and V. 

 geminata, var. racemosa. V. sessilis was very abundant on the 

 damp, sloping banks all around the larger of the water-works 

 ponds October 4. It continued to be abundant and healthy, 

 growing vegetatively until the first of November, when it began 

 to bear sexual organs. It was fruiting considerably the middle of 

 November. On the fourth of December it was looking yellowish, 

 unhealthy, and seemed to be loosened from the ground, due to the 

 ground freezing and thawing. On December 21, the ground was 

 covered with snow, but in places small patches of Vancheria could 

 be seen, unhealthy in appearance. Ripe oospores were found in 

 it. They were no doubt " seed " for next year's crop. On Janu- 

 ary 10 the banks were in the main covered with water due to a 

 rise in the pond, and no Vaucheria was to be seen. It did not 

 reappear before the close of the study, the first of August. 





